You don't have to feel bad about having the gug'mint on this. they are supposed to be in on this - the FDA. CFR Title 21 GMP's.
There are rules when you use/manufacture/import/decant/repackage/test API's (Active Pharmaceutical Ingredients).
The importer of record should have tested this material to spec. ( USP monograph).
The problem is that there are a huge number of hands that the material passes through before use. By the time it( China origin API) gets to the domestic manufacturer, it looks (on paper at least) that it came from a friendly, US FDA inspected, cGMP Compliant, ISO blessed, neighborhood Pharma that has been in the US for 100 years.
so it must be ok...
"Rules of Origin" play a big role in this deception. If you use trade rules, eventhough a raw chemical/API comes from China, if you import it into the US, and add a lot of value (Net Cost calc in NAFTA) or the product shifts a schedule B number in the Chapter or sub chapter level,due to intended use or processing, the product now "originates" the US according to NAFTA and other trade rules.